已知A=a^3-3a^2+2a-1,B=2a^3+2a^2-4a-5,求A-4(B-(A+B/2))
问题描述：
已知A=a^3-3a^2+2a-1,B=2a^3+2a^2-4a-5,求A-4(B-(A+B/2))
答
A-4[B-(A+B/2)]
=A-4B+4(A+B/2)
=A-4B+4A+2B
=5A-2B
=5(a^3-3a^2+2a-1)-2(2a^3+2a^2-4a-5)
=5a^3-15a^2+10a-5-4a^3-4a^2+8a+10
=a^3-19a^2+18a+5